1. Field of the Invention
The present invention relates to a photovoltaic light-polarizing element and a method of manufacturing the same.
2. Description of the Related Art
Generally, a polarizing plate passes only polarized light in a specific plane of oscillation. At this time, light components that have not passed through the polarizing plate are absorbed, and most of the luminous energy is dissipated as thermal energy.
As an example, energy consumption of a liquid crystal display will be explained. A liquid crystal display includes a liquid crystal panel formed by sandwiching a liquid crystal layer between two polarizing plates. The liquid crystal display displays an image by controlling the amount of, out of light emitted by a backlight serving as a light source, light components that pass through the two polarizing plates. When such a liquid crystal display is displaying white, the ratio of light passing through the liquid crystal panel to light emitted by the backlight is about 5%. In this case, the backlight-side polarizing plate absorbs most of the light emitted by the backlight. The backlight-side polarizing plate absorbs about 55% to 60% of the light emitted by the backlight. Most of the absorbed luminous energy is dissipated as heat. In addition, most of power to be consumed by the whole liquid crystal display is consumed by the backlight. The larger the screen size is, the stronger the tendency is. Under these circumstances, a polarizing plate with little energy loss is demanded.
In recent years, a dye-sensitized solar cell as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2008-41258 is expected to be put into practical use because it enables to manufacture a large-area element at a low cost and realize a flexible cell, as compared to a solar cell using silicon crystal. The principle of power generation of the dye-sensitized solar cell will briefly be described below. Dye molecules are excited upon absorbing light, and the electrons of the dye molecules are injected into titanium oxide that is a semiconductor. The dye molecules that have lost electrons obtain electrons from an electrolyte. Hence, a voltage difference is generated between the titanium oxide and the electrolyte. This voltage difference functions as a cell.
As described above, a polarizing plate with little energy loss is demanded. In a dye-sensitized solar cell as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2008-41258, dye molecules are isotropic with respect to light because they are given no specific direction of alignment. When dichroic molecules given a specific direction of alignment are used as the dye molecules, the dye-sensitized solar cell is expected to function as a polarizing element.